Drill



April 8, 1941, w A CHUN 2.237 901 DRILL Filed Oct. 7, 1958 Patented Apr. 8, 1941 UNITED STATES PATENT OFFICE DRILL William A. Chun, Houston, Tex.

Application October 7, 1938, Serial No. 233,752

Claims. (CI. 77-68) This invention relates to a drill and has particular relation to a novel type of twist drill particularly designed for use in drilling metal.

An object of the invention is to provide a drill of the stub, spiralled type having replaceable cutting blades which may be quickly changed, for renewal and having channels for cooling fluid through which the fluid may be cast on the front cutting edges of the blades.

Another object of the invention is to provide a drill of the character described having specially formed spiralled flutes for the delivery of the cuttings and wherein the cuttings will not congest and choke.

Another object of the invention is to provide a drill of the character described having adrive shaft, or shank, which may be formed integrally with, or detachable from the body of the tool and which is smaller in diameter than said body to provide space above the body to receive the cuttings and whereby the cuttings may be effectively lifted and removed from the bore upon removal of the drill.

It is another object of the invention to provide a drill of the character described having a relatively thick sturdy body whose bore engaging surfaces are coated with a substantially frictionless hard material.

It is another object of the invention to provide a drill having a spirally fluted body which is so formed as to provide a strong substantial core containing ample material to give unusual strength to this type of drill so that it will not be liable to be twisted ofi under heavy duty.

With the above and other objects in view the invention has particular relation to certain novel features of construction, arrangement of parts and use, examples of which are given in this specification and illustrated in the accompanying drawing, wherein:

Figure 1 shows a side elevation of the drill having a detachable shank, or driving shaft, shown in section.

Figure 2 shows a forward end view.

Figure 3 shows a side elevation taken at right angles to the view shown in Figure 1 showing the driving shaft or shank integral with the body of the tool.

Figure 4 shows a cross-sectional view taken on i the line 4-4 of Figure 3.

Figure 5 shows a cross-sectional view taken on the line 5-5 of Figure 3.

Figure 6 shows a side view of a cutting blade employed.

Figure 7 shows an end view thereof.

Figures 8 and 9 show side and edge views of another form of cutting blade, and

Figures 10 and 11 show a forward end view and a side elevation, respectively, of still another form of cutter that may be employed.

Referring now more particularly to the drawing wherein like numerals of reference designate the same parts in each of the figures, the numeral l designates the body of the tool. This body is of a general cylindrical form having a tapering, or conical, forward end face 2.

The body is formed with oppositely disposed grooves or flutes 3, 3 leading from the conical forward end face 2 to the opposite, or upper end of the body. These flutes are provided to serve as passageways for the cuttings upwardly into the space above the body as the work progresses and they are gradually widened upwardly to prevent congestion of the cuttings. The numeral 4 designates a driving shaft, or shank. This shaft may be of any desired length depending on the type of work to be performed and, as shown in Figure 1, it is detachable from the body. To provide for this detachment the body has a reduced outwardly threaded pin on its upper end on to which the adjacent end of the shank is threaded. The pin 5, adjacent the body is enlarged forming a blank extension which is snugly received by the smooth bore 1 of the shank, when the shank is screwed home, thus conducing to strength.

In the form shown in Figure 3 the shank 4a is formed integrally with the body. The shank, pin 5 and body are provided with an axial water course 8 extending therethrough to the forward end of the body as shown in Figures 1 and 4.

The forward end of the body is provided with a transverse, relatively deep, slot 9 to receive the transverse cutter blade ID. This cutter blade is seated snugly in said slot and its inner end is formed with a tenon I l which extends up into the water course 8, as shown in dotted lines in Figure 1. The opposite edges of the tenon l l are curved, as shown in Figure 7, to conform to the curvature of, and to fit snugly in, said water course of the head, and the tenon I l is of somewhat less transverse diameter than the inside diameter of the water course thus providing water passageways l2, as shown in Figures 2 and 4, along side the blade, one on each side, extending entirely to the forward end of the head. This is also indicated in dotted lines in Figure 1.

The cutter blade l0 terminates in the forwardly converging cutting edges 13, I3 and the flutes, or

channels 3, 3 have their forward ends located in front of the corresponding cutting edges l3 so that the cuttings will be delivered into said flutes. The cutter blade may be anchored to the body by means of suitable set screws H5, H1 therethrough which are screwed into the body as shown in Figure 4. The cooling fluid will be discharged through the pasageways 12 onto the point of the cutter I0.

Diverging downwardly from the water course 8, on opposite sides of the body are the upper and lower branches l5, IS the former of which are directed toward the side reaming edges ll of the cutter and the latter of which are directed toward the outer ends of the cutting edges l3. The cooling fluid will thus be delivered directly onto the cutting edges where the work is most severe so as to keep the same cool to the end that they will not be deteriorated by excessive heat.

The bore engaging surfaces (8, 18 of the head, that is, that portion of the head between the flutes are provided with a coating of hard frictionless material which will greatly reduce the friction between the body and the walls of the bore being formed.

While drilling the cuttings will be carried along the flutes 3 into the bore around the driving shaft, or shank 4, or id, which being reduced in diameter, are of a less diameter than that 9 of the body, to provide ample space for said cuttings and when the drill is withdrawn from the bore the major portion of the cuttings accumulating in the bore will be engaged by the adjacent end of the body and will be withdrawn from the bore made by the drill.

It is to be noted that the bottom of each flute is convex throughout the length of the flute as more clearly shown in Figure 5. This construction provides sufiicient material to form a very strong core for the body which will readily withstand any torsional strain to which the drill is likely to be subjected.

The blade used may be of any selected type, for example the blade Illa, is provided on its forward end with a spindle I9 surrounded by a bushing 20 retained in place by the circular retainer plate 2| which is fastened onto the outer end of the spindle by means of a set screw 22.

This type of blade may be inserted into the slot 9 and secured therein in the manner illustrated in Figure 4 and in use, the spindle is inserted into the outer end of a bore previously formed and upon operation of the tool, the cutting edges lllb of the blade, will form a smooth face around the outer end of the bore, as is necessary in certain types of work.

Another type of blade as lDc is illustrated in Figures 8 and 9. This type is similar to the blade I!) shown in Figures 1 and 2, with the exception that its cutting edges lllb are in stepped relation as clearly illustrated in Figure 8. This type of blade is secured in place in the same manner as the type shown in Figures 1 and 2.

The cutter illustrated in Figures 10 and 11 is shaped to form a bore which is annular in cross section. The shank or blade portion We is fitted into and secured in the slot 9 as illustrated in Figure 4. The forward portion of the cutter has a substantially tubular body 23 and its forward end terminates in the forwardly directed cutting edges 24 spaced apart therearound and arranged, when applied to the work, to form a bore which is annular in cross section.

The drawing is illustrative merely. Changes in the mechanical design of the tool may be made, as is obvious, the broad principle of the invention being defined by the appended claims.

What I claim is:

1. A drill comprising a body, a shank of less diameter than the body for driving the body, said shankand body having an axial water course therethrough and the forward end of the body having a transverse slot, a blade detachably secured in the slot, the diameter of the passageway through the body being greater than the minor diameter of the blade and said passageway forming outlets for a cooling fluid along opposite sides of the blade, said passageway having upper and lower, approximately parallel branches disposed to cast the cooling fluid in front of the blade on opposite sides of the body.

2. A drill comprising a body having an axial water course therethrough from end to end, the forward end of the body having a transverse slot, a blade secured in the slot and positioned to divide the passageway into separate channels one on each side of the blade.

3. A drill comprising a body having an axial water course therethrough from end to end, the forward end of the body having a transverse slot, a blade secured in the slot and positioned to divide the passageway into separate channels one on each side of the blade, said blade having forward end cutting edges and side cutting edges and said body having upper and lower branches leading from said passageway and disposed to cast a cooling fluid in front of the side cutting edges and at the outer ends of the end cutting edges.

4. A drill comprising an approximately cylindrical body having spiralled side flutes and an axial bore extending from end to end thereof and having a transverse slot at its forward end, a cutting blade having side and front cutting edges detachably secured in the slot by means of screws and a tenon on the inner end of the blade fitted in the passageway, said blade and tenon being shaped to allow a limited flow of fluid from the bore around the tenon and blade, the bottom of each flute being convex throughout the length of the body, said body having channels on opposite sides thereof connected to said core and disposed to cast fluid in front of the cutting edges of the blade at the side cutting edges and at the outer ends of the end cutting edges.

5. A drill comprising a short approximately cylindrical body having spiralled side flutes extending from end to end thereof, the body having a coating of hard facing material, a detachable blade on the forward end of the body having forward and side cutting edges, a portion of the body being relieved and. forming a. rim on the forward edges of the body between the flutes, the diameter of the body at the rims being equal to the width of the blade, said relief being very slight so that the body as Well as the rims will act as bearing faces 01' stabilizers to resist movement of the blade away from the metal cut.

WILLIAM A. CHUN. 

